This invention relates to a pipette controller.
For the operation of pipetting, one of the traditional ways is that liquids are taken up into a pipette by suction with operator's mouth and are kept therein by blocking one end of the pipette with operator's finger tip, then the liquids inside the pipette are delivered by removal or release of the blocking finger tip. It is readily seen that pipetting in such manner is quite inconvenient and unsuitable, because the amount of liquid being taken up and/or being delivered can't be well controlled, and also it is not hygienic, especially, when the liquid to be pipetted is destructive to one's health or has an unpleasing odor.
To obviate the necessity of using the operator's mouth and finger tip, it has been proposed to provide at one end of the pipette a controlling device for suction or exhaust operation. In the art of this controlling device, a cylinder-piston assembly has been employed, the piston is operable to slide back and forth inside the cylinder by means of a piston rod, which is connected to the piston and is held in resiliently depressible condition with a coiled spring, while the base of the cylinder is provided with a port adapted to connect with the mouthpiece of a pipette, such that, the travel of the piston inside the cylinder will control the suction or exhaust of the pipette when the jet of the pipette connected at the port of the cylinder is inserted into the liquid to be pipetted.
Although the above-mentioned controlling device is able to eliminate the intervention of operator's mouth and finger tip, the amount of liquid being sucked in or being delivered is still out of control.